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United States Department of Agriculture

Agricultural Research Service

Title: Complexation of Herbicides by Soluble Fulvic Acids

item Melon, Silvia - UCSC, PIACENZA
item Clapp, Charles
item Hayes, Michael - UNIV OF BIRMINGHAM
item Mingelgrin, Uri - ARO, BET DAGAN, ISRAEL
item Dowdy, Robert

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 30, 1995
Publication Date: N/A

Technical Abstract: Some commonly-used herbicides, such as napropamide, atrazine, and alachlor can complex with soluble humic substances, producing a significant effect on apparent solubility and mobility. The extent of complexation of the herbicides with fulvic acids, studied by an equilibrium dialysis method, was lower than expected, but about equal to that of the corresponding humic acids. Some extensive comparisons were required to select dialysis membranes of the appropriate type and pore size. Data from experiments with various concentrations of fulvic acids and herbicides were fitted to an equation which is analogous to the Langmuir adsorption isotherm. Additional complexes were prepared with **14C-labeled napropamide and a collection of well-characterized fulvic acids from soil, peat and water. Differences in complexation resulting from source and type of humic substance will be discussed.

Last Modified: 4/22/2015